Layout error in blazor 6 cshtml _host file after Visual Studio 17.10.1 update

So far I had set the layout to "null" in the _Host.cshtml file.

@{ Layout = null; }

So far, this has worked perfectly.

Since the update to Visual Studio 17.10.1 I get the error message: "Object reference not set to an instance of an Object".

From my perspective, this is only about the overarching HTML framework. I don't want to set a layout file here. I set the layout files via the "Routes" class or within the page. Why do I get an error now (since the update of VS)? How can I handle this error?

I have already tried to set the layout file to a String.Empty (""). Did not work either. Even removing the block itself did not lead to a solution.